2019/02/24 by Changhong Li, Li, Changhong
Physics and Astronomy · #Cosmology and Gravitation Theories #Cosmology and Nongalactic Astrophysics (astro-ph.CO) #Dark Matter and Cosmic Phenomena #FOS: Physical sciences #Galaxies: Formation, Evolution, Phenomena #General Relativity and Quantum Cosmology (gr-qc)
paper · pdf · doi:10.48550/arxiv.1902.08963
openalex publication_date 2019/02/24 · openalex created_date 2020/05/01 · openalex updated_date 2026/07/28
We investigate the co-evolution of dark matter (DM) density perturbation and metric perturbation in the WIMP paradigm. Instead of adopting the conventional assumption that DM starts out in thermal equilibrium, we propose a simple phase of DM production for the WIMP paradigm and extend our analysis to this phase. Being free from the envelop of thermal equilibrium, an amplified perturbative resonance between DM density perturbation and scalar modes of metric perturbation takes place during the DM production phase, and consequently results in a suppression of the tensor-to-scalar ratio of metric perturbation. By specifying the cosmic background with a typical realization of cosmic reheating, we establish a relation between DM particle mass mχ and the tensor-to-scalar ratio r in the WIMP paradigm, which also contains two reheating parameters, the reheating temperature TRf and the dissipative constant Γ0. Notably, for a sizeable parameter region of WIMP candidate and cosmic reheating, this relation predicts a smaller value of r in comparing with the conventional expectation obtained by assuming DM starts out in thermal equilibrium. Once the suppression of r is measured in future observations of primordial gravitational wave in CMB, this relation can be used to constrain mχ, TRf and Γ0 in principle.